Transportable strip chart recorder

ABSTRACT

A readily transportable strip chart recorder includes a disposable strip chart dispenser. The dispenser holds one rolled end of the strip chart and the free end passes over a writing surface and beneath a window exposing the strip chart above the writing surface. The dispenser is detachably mounted in a case with the free end of the strip chart adjacent a drive spool to be wound thereon when in use. The drive spool is powered by a battery driven motor. Two switches are employed to close the circuit between the battery and the motor. One switch is closed when the dispenser is in place in the recorder case, whereas the second switch is closed only after the strip chart is manually advanced on the spool. Battery terminals are exposed externally of the case for checking the battery without opening the recorder case.

United States Patent Johnson TRANSPORTABLE STRIP CHART RECORDER Jerry E.Johnson, Bellevue, Wash.

[75] Inventor:

[73] Assignee: Ryan Instruments, Inc., Seattle,

Wash.

[22] Filed: May 12, 1972 [21] Appl. No.: 252,929

[ 52] U.S. C1 346/136, 324/295, 346/145 [51] Int. Cl. G0ld 15/28 [58]Field of Search. 346/136, 145, 33 TP, 41, 116, 346/117; 73/3435; 324/295[56] References Cited UNITED STATES PATENTS 2,142,492 l/l939 Cannon346/93 X 2,578,803 12/1951 Holmberg et a1.. 346/136 X 2,640,099 5/1953Hull 324/295 2,776,569 l/1957 Biro 73/3435 3,545,004 12/1970 Alden346/145 X 3,713,170 l/l973 Kaufman 346/136 Primary Examiner-Joseph W.Hartary [5 7] ABSTRACT A readily transportable strip chart recorderincludes a disposable strip chart dispenser. The dispenser holds onerolled end of the strip chart and the free end passes over a writingsurface and beneath a window exposing the strip chart above the writingsurface. The dispenser is detachably mounted in a case with the free endof the strip chart adjacent a drive spool to be wound thereon when inuse. The drive spool is powered by a battery driven motor. Two switchesare employed to close the circuit between the battery and the motor. Oneswitch is closed when the dispenser is in place in the recorder case,whereas the second switch is closed only after the strip chart ismanually advanced on the spool. Battery terminals are exposed externallyof the case for checking the battery without opening the recorder case.

4 Claims, 6 Drawing Figures PATENTEDJANZZIHH sum 1 or 2 PAIENTED JAN 221974 SHEET 2 OF '2 FIG 41 FMS 5 TRANSPORTABLE STRIP CHART RECORDERBACKGROUND OF THE INVENTION 1. Field of the Invention This inventionpertains to strip chart recorders, and particularly strip chartrecorders of the type that are intended to be easily transportable foruse in transit shipments of produce or the like.

2. Description of the Prior Art Easily transportable strip chartrecorders of the type to which this invention pertains are presentlybeing utilized to record temperature or other environmental variables inshipments by rail, truck, air and boat. The purpose of these recordersis to measure the environmental variable, for example, temperature, fromthe beginning of a trip to its destination. This temperature recordingassures the receipient of the shipment that the goods shipped weremaintained at a desired safe temperature throughout the trip.

Strip chart recorders heretofore employed have utilized a manually woundspring as a source of power for driving the strip chart. As a result,the recorder has to be manually rewound each time it is received in thecentral depository. Prior art recorders also required time consumingthreading of conventional charts onto the storage spool and a drivespool. Furthermore, in prior art recorders customers were not alwaysable to obtain from the recording the information desired for severalreasons: (1) The vehicle operator or shipping foreman who wasresponsible for starting the drive mechanism and filling in the desiredwritten information at the beginning of the strip chart aften found thejob too complicated or too time consuming and neglected the task, thusresulting in either an unused strip chart or one having incompleteinformation or both; (2) The person Whose responsibility was to analyzeinformation recorded at the destination of the shipment often tooklittle care in removing the strip chart, resulting in a torn orotherwise damaged strip chart.

SUMMARY OF THE INVENTION Hand winding of prior art strip charts is toocostly and time consuming and it is thus an object of this invention toprovide a battery powered strip chart recorder. Furthermore, since ashipper desires to maintain an inventory of such recorders, it isdesirable to provide a battery circuit that will not be energized whilethe recorder is sitting idle awaiting use. It is also desirable that thebattery circuit not remain energized at the end of the shipment afteruse. The practice in this field at present is to return the recorder toa central depository, such as the recorder manufacturers facility, forreplacement of the strip chart, and inspection and maintenance, prior touse on another shipment. In general, the strip chart recorders aretransmitted between the depository and the shipper and the receiver anddepository by mail and thus it is desirable that the strip chartrecorder be lightweight to reduce postage cost.

It is thus another object of this invention to provide a battery poweredstrip chart recorder that has a battery circuit which is completed onlywhen a strip chart is in place ready for use and has been advanced apredetermined distance by the operator.

It is another object of this invention to provide a strip chart recorderwith an inexpensive expendable strip chart dispenser detachable from therecorder when not in use.

It is another object of this invention to provide a strip chart recorderthat has a replaceable readily available writing surface to manuallyrecord data on the strip chart prior to its use.

Basically the objects are obtained by providing a strip chart having acase, means in the case for holding a strip chart, battery powered drivemeans for moving the strip chart, manual override means for advancingthe strip chart, a smooth flat writing surface for entering data beforethe chart is advanced, switch means for completing the circuit to thebattery only when the strip chart is ready for use, and a transducer andstylus for recording the environmental variable when the strip chart isin use. In the preferred form battery terminals are exposed externallyof the case so that the battery may be checked without its removal fromthe case.

The invention also includes a strip chart dispenser comprising upper andlower portions that nest together to hold and-confine the strip charttherebetween. One of the portions has a container for holding a rolledend of the strip chart with the other end free for wrapping around thespool of a strip chart recorder. The upper portion is provided with awindow and the lower portion with a smooth writing surface. Thedispenser is of inexpensive plastic material intended to be disposed ofafter use so that the pointed stylus of the strip chart recorder alwayshas an unused writing surface with each new strip chart used.

BRIEF DESCRIPTION OF THE FIGURES OF THE DRAWING FIG. 1 is a transversesection taken along the line 11 of FIG. 2.

FIG. 2 is an isometric of a portable strip chart recorder embodying theprinciples of the invention.

FIG. 3 is a section taken along the line 3--3 of FIG. 2.

FIG. 4 is a schematic circuit diagram employed in the recorder of FIG.2.

FIG. 5 is a section through the drive means 16.

FIG. 6 is a fragmentary section similar to FIG. 5 showing a closedswitch position.

DESCRIPTION OF THE PREFERRED EMBODIMENTS As best shown in FIG. 1, theportable strip chart recorder of this invention employs a case 10, atransducer 12 for sensing some environmental variable, such as pressureor temperature, primarily temperature in this application, a strip chartdispenser 14, a strip chart driving means 16 for advancing the stripchart, and a battery and battery circuit 18 for powering the drivemeans.

As is well understood in this art, the case 10 is relatively small,approximately 5 inches by 3 inches by 2 inches so that it is easilytransportable by mail. The case is of tough shock resistant material andincludes a base 20 having posts 21 for attaching the case to the wall ofthe vehicle. A cover or top 22 is hinged to the base 20. The transducer12 is secured to the top and is provided with a pressure-scribing stylus24 that engages a strip chart 26 when the top is closed onto the base. Alatch mechanism 26 is provided with mating slots 26a and 26b to receivea wire or other sealing strip to lock the top to the base to assuremaximum security against tampering.

The drive means 16 includes a drive spool 30 having a manually-drivenwheel 32 and a gear 34 mounted on an axle 36. A spool core 38 isintegrally secured to the wheel 32 and receives the strip chart in awell known manner, such as by hooking a tab of the strip chart over acatch mechanism 39 to secure it to the core for winding. Springfasteners 40 bias the wheel and gear toward one another on the axle 36so that they move through frictional engagement as an integral unit. Thewheels 32 and 38, however, can be moved independently of the gear 34 byapplying sufficient force to the wheel to overcome the frictionalengagement of the spring washers. This arrangement provides a means formanually overriding the battery powered drive to advance the strip chartrelative to the gear 34.

The gear .34 is driven through a drive train connected to a batterypowered clock motor 42 of conventional construction. The clock motor hasan output shaft which is keyed to a first drive gear 44 (FIG. 1). Thefirst drive gear meshes with a second drive gear 46. As is readilyapparent to one skilled in the art, the relative sizes of the drivegears 44 and 46 may be interchanged to provide various rates of movementof the strip chart. For example, the embodiment illustrated shows a 1:2gear ratio to provide a-30-day strip chart movement. Other typicalratios are 1:1 and 2:1 to provide -day and 8-day strip chart recordings,respectively. The gear 46 is coupled via a shaft to a bevel gear 48which in turn meshes with a second bevel gear 50. Bevel gear 50 mesheswith a gear 51 that in turn meshes with the gear 34.

Since the strip chart recorder may sit idle both before and aftershipment for many days, it is necessary that the battery be disconnectedfrom the circuit except when actually in use in making a recordingduring a shipment. It is thus a unique feature of this invention toprovide a circuit to assure conservation of the battery. For thispurpose the circuit is provided with a first switch 52 and a secondswitch 54. The first switch 52 is normally spring-biased out ofengagement with contactor 56 which forms part of the battery circuit.The switch is moved into contact with contactor 56 to partially completethe battery circuit by a pin 58 attached to the underside of the stripchart dispenser 14. The pin closes the switch 52 only when the stripchart dispenser is in place as shown in FIGS. 2 and 3, for example, andthus when the dispenser is removed from the case 10, the battery circuitis opened.

The second step for completing the battery circuit occurs when thesecond switch 54 is also closed. For this purpose, wheel 32 is providedwith a notch 60 large enough to allow the switch 54 to pass through. Theswitch 54 is biased to move to the left as shown in FIGS. 5 and 6 intothe position shown in FIG. 6 which closes with a contact to complete thebattery circuit. It is a unique feature of this invention that thesecond switch 54 is closed automatically by the advancing of the stripchart prior to its use. In the use of the strip chart recorder a shippermust enter on the strip chart certain data, such as date, time, shipper,contents, consignee, destination, etc. This information is invaluableginning of the strip chart. To enter this data the shipper must manuallyadvance the strip chart and then write the information at the prescribedlocation. The advancement occurs by rotating the wheel 32 in thedirection of the arrows shown in FIG. 4. As the strip chart is advancedthe notch 60 on the wheel is also rotated into alignment with the switch54. When the notch is aligned, the switch snaps through the notch 60closing the battery circuit, thus energizing the drive motor 42. Withthe battery circuit completed the strip chart begins to advance at thedesired speed setting.

When the shipment reaches its destination, the strip chart is removedand the recording with the data written in by the shipper is analyzed toassure that the shipment traveled at the desired temperature. To examinethe strip chart the dispenser is freed from the case and the remainingstrip chart stripped from the core 38. As the dispenser is lifted, thepin 58 is removed from engagement with the first switch 52, allowing theswitch to open, thus de-energizing the battery circuit. The receiverthen places therecorder, without the strip chart dispenser, into themail for delivery back to a central depository. At the depository a newstrip chart dispenser is placed into the case and threaded onto the coreand the switch 54 is reset against the inside surface of the wheel 32.

Another unique feature of the invention is that the battery 18 has apair of terminals connected to two set screws 64 which are exposed tothe exterior of the case (as best shown in FIG. 3). This feature enablesan inspector at the depository to examine the potential of the batterymerely by placing voltmeter probes on the two terminals 64. As a result,removal of the battery is necessary only for replacement. Sincethousands of recorders are handled in the depository, this savesconsiderable time.

Another unique feature of this invention is the use of a strip chartdispenser 14 that is inexpensive and expendable. The dispenser is alsodesigned to facilitate removal of the strip chart after use and initialthreading of the strip chart into the recorder. In practice it has beenfound that the foreman or clerk at the destination is often unfamiliarwith the use of strip charts and if a substantial amount of winding orunthreading is required, the strip chart is often damaged, ruining therecord. To overcome this problem the instant invention provides afoolproof means of removing the strip chart to assure its usefulness.For this purpose the dispenser 14 is provided with an upper portion oflightweight inexpensive plastic. The upper portion snaps over intolocking engagement with a lower portion 74 provided with a smoothwriting surface 76. Ribs 77 are provided on the underside of the lowerportion to rigidify the writing surface. A window 72 is provided overthe writing surface. The smooth writing surface allows entry ofhand-written information onto the strip chart and also assures that thestylus 24 has a smooth surface to act on for each strip chart. It hasbeen found that for transit shipments the ideal recording medium is apressure sensitive strip chart paper with a pressure stylus 24. Thestylus 24 must be sharp to make a fine legible line and as a result,repeated movement of the stylus along the same recording path canscratch a line into the surface below the strip chart. Thus, by makingthe writing surface part of the disposable dispenser the stylus isuniquely provided with a new writing surface for each shipment.

During manufacture the upper and lower portions of the dispenser arejoined at a hinge 78. The lower portion is provided with a container 80in which is nested a rolled end of a strip chart. To load the dispenserthe upper portion is swung away from the lower portion and the rolledend of the strip chart is seated into the container 80. Next the freeend of the strip chart is slid along the lower portion. The writingsurface of the lower portion is recessed as at 82 to assist in guidingthe strip chart to keep it in accurate alignment. Next, the upperportion is snapped over the lower portion, securely holding the stripchart therebetween, but holding the strip chart with only a slightamount of friction so that it may be easily pulled out of the dispenserand wound on the core 38.

The pin 58 is integrally molded into the bottom of the lower portion 74and fits through an opening 84 to engage the switch 52. The lowerportion is also provided with a forward vertical flange 86 and a pair ofspaced guide openings 88. The guide openings 88 fit over a pair of guidepins 90 in the base 20 to position and hold the dispenser in the base.Two spaced posts 92 hold the dispenser down in the case. The plasticmaterial of the upper and lower portions 70 and 74 is sufficientlyresilient to allow a force fit between the posts 92. To remove thedispenser the user need only lift the dispenser about the pins 88 andmove it forward in the case. By pressing through the window to hold thestrip chart, the strip chart may then be unwound from the spool bypulling it, using the dispenser as a handle.

While the preferred form of the invention has been illustrated anddescribed, it should be understood that variations will be apparent toone skilled in the art without departing from the principles of theinvention. Accordingly, the invention is not to be limited to thespecific embodiment described, but only by a literal interpretation ofthe claims appended hereto.

I claim:

1. A portable strip chart recorder comprising a case having a base andtop, mounting means in said case for holding a strip chart, drive meansin said case for advancing said strip chart, a battery circuit forpowering said drive means, a transducer for sensing an environmentalvariable and having a stylus engageable with said strip chart, switchmeans positionable for closing said battery circuit to power the drivemeans and for opening said circuit to conserve the battery, and meansfor manually advancing said strip chart and overriding the drive meanswhen initiating use thereof, said mounting means including a disposablechart dispenser removable from said case and having means for accuratelypositioning the dispenser in said case, said dispenser including a lowerportion and an upper portion, a window in said upper portion forexposing a strip chart to said stylus and for manually writing on thestrip chart prior to closing the top, a container on saiddispenser forholding a rolled end of strip chart and means for guiding the free endof the strip chart between said upper and lower portions, said drivemeans including a spool operable to be secured to said free end of thestrip chart, said dispenser being detachable from said spool as well assaid case whereby the dispenser contains only the strip chart and thusis expendable at a minimum cost, said lower portion having a smoothwriting surface disposed opposite said window to facilitate writing onsaid chart and to provide a new writing surface for the stylus, saidswitch means including a first switch for partially completing saidcircuit, said lower portion having a switch operator engageable withsaid first switch for closing said first switch only when the dispenseris in said case whereby removal of said dispenser opens said circuit toconserve the battery.

2. A portable strip chart recorder comprising a case having a base andtop, mounting means in said case for holding a strip chart, drive meansin said case for advancing said strip chart, a battery circuit forpowering said drive means, a transducer for sensing an environmentalvariable and having a stylus engageable with said strip chart, switchmeans positionable for closing said battery circuit to power the drivemeans and for opening said circuit to conserve the battery, and meansfor manually advancing the strip chart and overriding the drive meanswhen initiating the use thereof, said mounting means including adisposable chart dispenser removable from said case and having means foraccurately positioning the dispenser in said case, said switch meansincluding a first switch for partially completing said circuit and asecond switch for finally completing said circuit, means on saiddispenser for closing said first switch only when said dispenser is insaid case, and means on said strip chart manual advancing means forautomatically completing said circuit when said dispenser is in saidcase and said strip chart is manually advanced whereby the circuit isclosed by advancing the strip chart and is open both prior toadvancement and after the dispenser is removed.

3. A portable strip chart recorder comprising a case having a base andtop, mounting means in said case for holding a strip chart, drive meansin said case for advancing said strip chart, a battery circuit forpowering said drive means, a transducer for sensing an environmentalvariable and having a stylus engageable with said strip chart, switchmeans positionable for closing said battery circuit to power the drivemeans and for opening said circuit to conserve the battery, and meansfor manually advancing the strip chart and overriding the drive meanswhen initiating use thereof, said switch means including a movablecontact and means on said strip chart manual advancing means foractuating said contact to close the battery circuit whereby the circuitis automatically closed during the period the strip chart is beingmanually advanced, said mounting means including a disposable chartdispenser removable from said case and having means for accuratelypositioning the dispenser in said case relative to said drive means,said dispenser including a lower portion, an upper portion, a dischargeopening, and an enlarged window in said upper portion for exposing thestrip chart to said stylus and being large enough for manually writingon the strip chart prior to closing the top, said lower portion having asmooth writing surface disposed opposite said window to facilitatewriting on said chart and to provide a new writing surface for thestylus, a container on said dispenser for holding a rolled end of stripchart, and means provided on said upper and lower portions between saidwindow and said discharge opening for quid ing the chart between saidupper and lower portions and through said discharge opening, said driveincluding a spool operable to be secured to said free end of the stripchart as it leaves said discharge opening, said dispenser beingdetachable from said spool as well as said case whereby the dispensercontains only the strip chart and thus is expendable at a minimum cost.

opening said circuit to conserve the battery, and means for manuallyadvancing the strip chart and overriding the drive means when initiatinguse thereof, said switch means including a movable contact, and means onsaid strip chart manual advancing means for actuating said contact toclose said circuit upon the manual advancement of said strip chart wheninitiating use thereof.

* a: a: l

1. A portable strip chart recorder comprising a case having a base andtop, mounting means in said case for holding a strip chart, drive meansin said case for advancing said strip chart, a battery circuit forpowering said drive means, a transducer for sensing an environmentalvariable and having a stylus engageable with said strip chart, switchmeans positionable for closing said battery circuit to power the drivemeans and for opening said circuit to conserve the battery, and meansfor manually advancing said strip chart and overriding the drive meanswhen initiating use thereof, said mounting means including a disposablechart dispenser removable from said case and having means for accuratelypositioning the dispenser in said case, said dispenser including a lowerportion and an upper portion, a window in said upper portion forexposing a strip chart to said stylus and for manually writing on thestrip chart prior to closing the top, a container on said dispenser forholding a rolled end of strip chart and means for guiding the free endof the strip chart between said upper and lower portions, said drivemeans including a spool operable to be secured to said free end of thestrip chart, said dispenser being detachable from said spool as well assaid case whereby the dispenser contains only the strip chart and thusis expendable at a minimum cost, said lower portion having a smoothwriting surface disposed opposite said window to facilitate writing onsaid chart and to provide a new writing surface for the stylus, saidswitch means including a first switch for partially completing saidcircuit, said lower portion having a switch operator engageable withsaid first switch for closing said first switch only when the dispenseris in said case whereby removal of said dispenser opens said circuit toconserve the battery.
 2. A portable strip chart recorder comprising acase having a base and top, mounting means in said case for holding astrip chart, drive means in said case for advancing said strip chart, abattery circuit for powering said drive means, a transducer for sensingan environmental variable and having a stylus engageable with said stripchart, switch means positionable for closing said battery circuit topower the drive means and for opening said circuit to conserve thebattery, and means for manually advancing the strip chart and overridingthe drive means when initiating the use thereof, said mounting meansincluding a disposable chart dispenser removable from said case andhaving means for accurately positioning the dispenser in said case, saidswitch means including a first switch for partially completing saidcircuit and a second switch for finally completing said circuit, meanson said dispenser for closing said first switch only when said dispenseris in said case, and means on said strip chart manual advancing meansfor automatically completing said circuit when said dispenser is in saidcase and said strip chart is manually advanced whereby the circuit isclosed by advancing the strip chart and Is open both prior toadvancement and after the dispenser is removed.
 3. A portable stripchart recorder comprising a case having a base and top, mounting meansin said case for holding a strip chart, drive means in said case foradvancing said strip chart, a battery circuit for powering said drivemeans, a transducer for sensing an environmental variable and having astylus engageable with said strip chart, switch means positionable forclosing said battery circuit to power the drive means and for openingsaid circuit to conserve the battery, and means for manually advancingthe strip chart and overriding the drive means when initiating usethereof, said switch means including a movable contact and means on saidstrip chart manual advancing means for actuating said contact to closethe battery circuit whereby the circuit is automatically closed duringthe period the strip chart is being manually advanced, said mountingmeans including a disposable chart dispenser removable from said caseand having means for accurately positioning the dispenser in said caserelative to said drive means, said dispenser including a lower portion,an upper portion, a discharge opening, and an enlarged window in saidupper portion for exposing the strip chart to said stylus and beinglarge enough for manually writing on the strip chart prior to closingthe top, said lower portion having a smooth writing surface disposedopposite said window to facilitate writing on said chart and to providea new writing surface for the stylus, a container on said dispenser forholding a rolled end of strip chart, and means provided on said upperand lower portions between said window and said discharge opening forquiding the chart between said upper and lower portions and through saiddischarge opening, said drive including a spool operable to be securedto said free end of the strip chart as it leaves said discharge opening,said dispenser being detachable from said spool as well as said casewhereby the dispenser contains only the strip chart and thus isexpendable at a minimum cost.
 4. A portable strip chart recordercomprising a case having a base and top, mounting means in said case forholding a strip chart, drive means in said case for advancing said stripchart, a battery circuit for powering said drive means, a transducer forsensing an environmental variable and having a stylus engageable withsaid strip chart, switch means positionable for closing said batterycircuit to power the drive means and for opening said circuit toconserve the battery, and means for manually advancing the strip chartand overriding the drive means when initiating use thereof, said switchmeans including a movable contact, and means on said strip chart manualadvancing means for actuating said contact to close said circuit uponthe manual advancement of said strip chart when initiating use thereof.